Inconel® 625
Inconel 625 is a nickel-chromium-molybdenum alloy containing niobium. This addition acts to stiffen the alloy matrix, providing high strength without a strengthening heat treatment. It is globally recognized for its phenomenal resistance to pitting, crevice corrosion, and high-temperature oxidation.
- Common Forms: Pipe, Fittings, Flanges, Sheet, Bar.
- Key Feature: High strength + outstanding aqueous corrosion resistance.
- Corrosion: Immune to chloride-ion stress-corrosion cracking.
- Temperature: Service range from cryogenic to 1800°F (982°C).
Inconel 625 is one of the most versatile materials available. It solves the dual problem of requiring high mechanical strength and resistance to severe corrosive environments. Whether in sub-zero marine environments or high-temperature jet engine exhausts, 625 performs reliably.
Pitting Resistance
The high Molybdenum (9%) content provides exceptional resistance to localized attack (pitting and crevice corrosion) in seawater and chemical salts.
High Strength
The "Solid Solution Strengthening" effect of Niobium and Molybdenum gives it tensile strength significantly higher than Inconel 600, without needing precipitation hardening.
Fabricability
Despite its strength, it possesses good ductility and weldability, making it easier to fabricate into complex plant equipment compared to other superalloys.
| Element | Content (%) |
|---|---|
| Nickel (Ni) | 58.0 min (Balance) |
| Chromium (Cr) | 20.0 - 23.0 |
| Molybdenum (Mo) | 8.0 - 10.0 |
| Niobium (Nb) + Ta | 3.15 - 4.15 |
| Iron (Fe) | 5.0 max |
| Manganese (Mn) | 0.50 max |
| Carbon (C) | 0.10 max |
*Note: The combination of Mo and Nb is what gives Alloy 625 its unique properties.
| Product Form | ASTM / ASME Standards |
|---|---|
| Pipe & Tube (Seamless) | ASTM B444, ASME SB444 |
| Pipe (Welded) | ASTM B705, ASME SB705 |
| Plate, Sheet, Strip | ASTM B443, ASME SB443 |
| Bar & Rod | ASTM B446, ASME SB446 |
| Fittings | ASTM B366, ASME SB366 |
| Forgings | ASTM B564, ASME SB564 |
| Property | Typical Values (Room Temp) |
|---|---|
| Tensile Strength | 120 - 150 ksi (827 - 1034 MPa) |
| Yield Strength (0.2% Offset) | 60 - 95 ksi (414 - 655 MPa) |
| Elongation | 30 - 60 % |
| Hardness (Brinell) | 175 - 240 HB |
*Note: Significantly stronger than Inconel 600 or 601 in the annealed condition.
Marine Engineering
Propeller blades, submarine propulsion motors, exhaust ducts, and sheathing for undersea cables.
Pollution Control
Scrubbers, stack gas reheaters, and dampers in flue gas desulfurization (FGD) systems.
Aerospace
Ducting systems, engine exhaust systems, fuel and hydraulic line tubing, and turbine shroud rings.
Chemical Processing
Equipment handling superphosphoric acid, hydrofluoric acid, and sour gas.
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